1. Field of the Invention
The present invention relates to a resin product for a vehicle, made by welding a plurality of resin members by vibration welding.
2. Description of the Related Art
Generally, in regard to a resin product for a vehicle, produced by joining a plurality of resin members, such as, e.g., a spoiler for adjusting an airflow around a vehicle body, an art using vibration welding has been known. Welding by using vibration welding has advantages that cost reduction can be achieved by reducing steps of joining process even for a large-size resin product for vehicles and also a sufficient joint strength can be easily assured.
As a rear spoiler made by the aforementioned vibration welding, there has been known a rear spoiler shaped linearly in a vibration direction, that is joined by vibration welding performed with an outer surface of a hollow inner member being covered with an outer member (for example, Japanese Unexamined Patent Application Publication No. 2004-106765).
Furthermore, there has been such a rear spoiler that, as a jig used to hold the members by adding pressure in a vertical direction at the time of vibration welding, in addition to a first jig and a base jig both arranged in the vertical direction, an auxiliary jig is also arranged in a direction perpendicular to the vibration direction. By arranging these three jigs in the direction perpendicular to the vibration direction in this manner, even with a structure having welded portions separated into two locations in the direction perpendicular to the vibration direction, the welded portions can be individually welded by pressure applied by the jigs that are arranged with respect to the welded portions on a one-to-one basis (for example, Japanese Unexamined Patent Application Publication No. 2010-208058).
Furthermore, recently there has been a trend for a vehicle shape to have a more curved shape in terms of a design, thereby demanding a resin product for a vehicle to be shaped in accordance with such a vehicle design.
However, those disclosed in Japanese Unexamined Patent Application Publication Nos. 2004-106765 and 2010-208058 described above, are such as to produce a spoiler designed linearly in a longitudinal direction by performing vibration welding to two resin members shaped linearly in the vibration direction. That is, those are produced with no consideration for application to a resin product designed to be curved in the longitudinal direction.
Regarding the problem caused when vibration welding is performed with an inner side of a resin member thus shaped curvedly in the vibration direction being brought in abutment with another resin member, an explanation is given with reference to a schematic configuration shown in FIG. 13.
As shown in FIG. 13, in the case where two members K1, K2, shaped to have curved end portions are vibration-welded in a vibration direction Q in their longitudinal direction, an angle θ1 of a contact surface between the two members with respect to the vibration direction Q is extremely decreased at a point J1 around the center portion. This causes sufficient frictional heat by friction in the contact surface even at the time of vibration welding, so that a sufficient strength can be easily obtained.
However, in the case where the two members K1, K2 are shaped to become more curved as approaching to the end portions, an angle θ2 of the contact surface between the two members with respect to the vibration direction Q is undesirably increased at a point J2 around each end portion. This makes it difficult to cause friction in the contact surface even in an attempt to perform vibration welding in the vibration direction Q, thereby causing a problem that sufficient frictional heat cannot be obtained and also a welding strength cannot be obtained enough.
Furthermore, if a curved part is welded, screwed, or fixed using an adhesive in a separate step, the cost is undesirably increased due to the increased number of production steps and the like.
The present invention has been achieved in consideration of such circumstances, and an object thereof is to provide a resin product for a vehicle, which can be welded, even in a shape having a part curved in a vibration direction, with a sufficient strength by means of vibration welding.